Pipeline transportation of energy sources has never been so important to the energy infrastructure and consumption of developing nations. Our economies and base of manufacturing rely heavily on the safe and timely provision of energy that may be transported through pipelines in different forms. This quest for energy sources has made the necessity of pipelines an inherent component in our society as a result of their ability to economically transport large volumes of liquids and gases. From crude oil to liquid natural gas, to tar sand oil: the reliable delivery of these valuable commodities for processing or immediate use has never been so important to powering our homes, businesses, towns, cities and nations. The transportation of energy sources often occurs over vast distances through rough terrain, difficult environments, important agricultural lands, valuable ecosystems, extreme weather, hydrologically sensitive areas, and potentially unstable regions.
However, an inherent problem with energy source pipelines is the catastrophic impact a spill or leak can have on our environments, ecosystems, humans and wildlife. The risk to valuable water reserves including but not limited to: the wetlands, streams, rivers, and aquifers which in some circumstances is the main source of natural clean drinking water for large segments of population bases is immeasurable. Further, as a result of the range of damage that may be caused due to the potentially toxic transported materials, the damage can persist for years.
In 2007, there were 161,000 miles of onshore pipeline transporting hazardous materials (chiefly petroleum products) in the US. From 2007 to 2011, significant spillage incidents averaged 117 per year, and released an average of 80,000 barrels of hazardous product per year into the environment for a total spillage of approximately 400,000 barrels. Other countries and nations throughout the world have experienced similar spill occurrences per mile of pipeline. There is now a great need for a pipeline system that will not only reduce the severity and occurrences of such releases, but concurrently and autonomously actively monitors a pipeline to enable the owner/operator to be able to know in real time precisely where and when there is a concern, exactly what the issue is at any specific location throughout the entire pipeline, and the appropriate response needed to affect said concern. What is needed is an effective containment, autonomous, self monitoring, and active notification system.
Safe pipelines are the key to moving forward in our energy dependant world. The majority of existing petrochemical pipelines in use are fabricated as single wall pipes, may be buried or above ground, and may have an insulating jacket. Whilst a single wall pipe has lower construction and repair costs than a double walled type, single wall pipe failures can release transported toxic materials to the surroundings with devastating results. Significant releases can occur before detection, resulting in catastrophic damage to the environment, humans and wildlife, as well as loss of goodwill, costly clean up operations and litigation against the pipeline owner/operator.
A number of pipeline leak detection systems have been designed to address the aforesaid problems, some of which are described below:
U.S. Pat. No. 6,032,699 by Graeber et al uses a dual wall system with a pressurized gas or liquid in the containment pipe. Leaks are detected by pressure sensors at sealed pipe segments, and a local audio or visual alarm is set. The design intent is for gas station fuel distribution. This design is not suitable for long pipelines due to the limited type of sensors and inability to communicate over long distances.
U.S. Pat. No. 5,433,191 by McAtamney uses a dual wall system zoned off by annular rings and detects the presence of liquids, including hydrocarbons using capacitive sensors. Each sensor is connected to a common panel for local audio and visual alarm indications. The design intent is for a storage tank next to an industrial plant. This design is not suitable for long pipelines due to the limited type of sensors and inability to communicate over long distances.
U.S. Pat. No. 6,970,808 by Abhulimen et al uses general pipeline parameters such as flow and pressure at monitoring stations along the line as inputs to central analysis and simulation algorithms to deduce when a spill has occurred. Since direct measurement at a spill location is not used, the method is subject to false alarms such as an operator changing a valve position, and has insufficient accuracy to detect small but significant leaks. Also, the method has no provision for spill containment.
U.S. Pat. No. 7,500,489 by Folkers uses a dual wall pipeline with brine in the container pipe at a higher pressure than the carrier pipe. The brine chambers are connected via tubes to a gas-brine reservoir, and leaks are detected by a float in the reservoir. To minimize brine requirements, the interstitial space is small, but this makes the example subject to false alarms from carrier pipe expansion and contraction due to carrier transported gas or liquid pressure or temperature changes. The use of brine also restricts use to non-corrosive carrier pipe materials such as fiberglass. Using a non-corrosive liquid such as glycol risks releasing toxic material to the environment. The small interstitial space also offers little protection for the carrier pipe from excavation equipment accidental damage.
U.S. Pat. No. 7,441,441 by Omer uses a dual wall pipeline with hydraulic fluid in the container pipe at a higher pressure than the carrier pipe. A break in the carrier pipe causes a hydraulic fluid pressure drop which is sensed. The pipeline is segmented by valve stations which close off the pipeline flow when the pressure drop is sensed. This method cannot distinguish between carrier pipe and container pipe leaks, and has a great potential for leaking hydraulic fluid into the environment. The system has no provision for reporting a leak, and it's isolation capability is limited to the distance between valve stations.
U.S. Pat. No. 6,489,894 by Berg uses a vacuum between the inner and outer pipes and a vacuum switch manifolded among more than one container section to determine when a leak has occurred. The patent refers to previous art which did not use a manifold, and therefore were more costly. The design intent, despite the title, is for use in storage tanks, not long pipelines. Scaling Berg's approach (or any of his referenced art approaches) to typical pipelines is cumbersome at best, and Berg's approach provides poor leak isolation information.
U.S. Pat. No. 6,123,110 by Smith et al provides a method for rehabilitating a single wall pipe into a double wall pipe by inserting a new smaller diameter pipe with stud spacers inside the existing pipe. The spacers provide for installing a leak detection system, examples of which are referred to but not well described. A manhole adapter is described. Smith's approach disadvantageously uses an old pipe for containment which is likely to fail when pressurized by a leak from the new inner pipe, and it makes no claims for leak isolation and reporting capability.
US Patent 2005/0212285 by Haun describes a method for reducing stresses in joints between the inner and outer pipe, and makes no claims for leak detection, isolation and reporting.
U.S. Pat. No. 3,943,965 by Matelena is a triple wall pipe which passes a glycol coolant between the outer and middle pipe to prevent hot oil or petroleum gas from melting the surrounding permafrost. The space between the middle pipe and carrier pipe is a vacuum insulator. Hydrometer and pressure sensors in the vacuum detect leaks from the coolant and carrier pipes. A photoelectric sensor detects changes in the glycol coolant transparency as an additional leak detection method. An oil/glycol separator and pump return leaked oil back into the carrier pipe. Matalena's approach is cumbersome to implement due to the triple wall construction, the large volumes of glycol needed, and the leak prone plumbing needed to cool and distribute the glycol. There is no method defined for preventing the glycol from leaking into the permafrost. The oil/glycol separator is unlikely to be able to accommodate large flow rate oil leaks. And there is no method defined for collecting and reporting sensor data.
U.S. Pat. No. 3,721,270 by Wittgenstein uses a plastic jacket around the pipe which is connected to mechanical liquid sensors and collection vessels at low points in the pipeline. In essentially horizontal pipeline sections, water fills the interstitial space and pressure sensors detect the effects of leaks. The invention claims that the leaking fluid pressure is attenuated by permitting relatively unencumbered passage to the collection vessel, therefore an inexpensive jacket may be used. Considering that pipelines transport petroleum products at high pressure, a leak of even moderate rate would quickly fill up any practical sized collection vessel, causing the jacket to burst. Also, there is no teaching of leak location reporting.
U.S. Pat. No. 3,863,679 by Young uses a casing around the pipe to transfer leaking fluid to collection casings at intervals along the pipe. The collection casing includes a pump for transferring the leaking fluid back into the pipe. While the method would seem to work for small leaks, even moderate leaks would require a large pump at each collection casing, which would be a considerable expense, considering it would seldom be required. Reducing that expense by spacing the pumps far apart results in a long section of pipe which would have to be possibly dug up and cleaned before being returned to service. Leak location reporting is inaccurate, being limited to the distance between collection casings.
U.S. Pat. No. 8,131,121 by Huffman uses multiple acoustic fiber optic cables either spirally wrapped around the pipe or running linearly down the pipe longitudinal axis and arranged side by side around its circumference. Multiple cables are claimed necessary for detection capability. Disadvantageously, the spiral cables require calibration for accurate leak location by installing acoustic generators at measured distances on the pipes during construction and recording the results. And the spiral cables limit the length of pipe which can be sensed, resulting in more monitor stations being required. While as few as one linear cable is taught, multiple cables are taught for increased performance, which is a complex approach. There is no teaching of leak containment.
U.S. Pat. No. 8,177,424 by Wokingham et al uses a fiber optic cable connected to temperature sensor pads located at discrete distances along the pipeline. Leaks are detected by temperature variations at sensor pad locations. Leak location accuracy is limited to the distance between sensor pads, and since the sensor pad readings are affected by heat transfer with the surrounding sea water, small to moderate leaks are unlikely to be detected. There is no teaching of leak containment.
U.S. Pat. No. 6,378,987 by Alliot uses a fiber optic cable fastened external to the pipe insulation, except at initially un-insulated field joints at discrete distances along the pipeline where the cable is wrapped around the joint. Insulation is then applied to the field joint. Leaks are detected by temperature variations at field joint locations. Leak location accuracy is limited to the distance between field joints, and small leaks are unlikely to be detected, since they do not adequately affect pipeline temperature. There is no teaching of leak containment.
Thus, there is a need for an improved pipeline which addresses the above-noted problems.